Screw starter



May 8, 1962 A. E. ERICSON SCREW STARTER Filed Nov. 2, 1960 INVENTOR.

194/ f'. fR/CJOA/ A 7' TOIPA/EYS United States Patent Ofifice 3,033,254 Patented May 8, 1962v 3,033,254 SCREW STARTER Alf E. Ericson, 1557 N. Saginaw St., Lapeer, Mich. Filed Nov. 2, 1960, Ser. No. 66,794 4 Claims. (Cl. 145-50) This invention relates to improvements in the construction of a device which can be placed in gripping and driving engagement with a screw for starting the screw into a hole, and is particularly directed to a device of this type suitable for use with cross-slotted screws.

The device of the present invention is characterized by the provision of a pair of blades which engage the slotted portion of the screw. One of these blades is secured to a suitable handle for rotation therewith, and will be called the driver blade. The other blade will be called the gripper blade. It is rotatably mounted on the handle by suitable means and normally urged for rotation relative to the driver blade. Preferably the direction of this normally urged rotation of the gripper blade is the same as the direction in which the handle must be rotated to tighten the screw in hole. Detent means hold the gripper blade in a set position where both blades can be engaged with the slotted portion of the screw, these detent means being releasable in response to such engagement. When the detent means are released, the gripper blade rotates and the screw is engaged between the driver and gripper blade and held in an endwise position for inserting and starting movements. When the turning moment necessary to rotate the screw into the hole increases beyond a certain amount, the force urging the gripper blade into gripping engagement with the screw is overcome, and further turning of the handle results in returning the gripper blade to its initial position where it is engaged and held by the detent means. The device is then withdrawn from the screw which has been started and is set for engagement in the slotted portion of another screw.

In the preferred construction to be described herein, the gripper blade is mounted on a collar which is rotatably carried by the handle and held in assembled relation with the handle by the driver blade whose outer end includes a headed portion which overlaps the collar. Means in the form of a combined torsion and compression spring urges the collar into engagement with the headed portion of the driver blade and at the same time urges the collar rotatably relative to the driver blade. With this construction the driver blade also forms part of the detent means, the headed portion thereof being engageable in a detent notch formed in the collar.

Another preferred feature of the construction is that when the gripper is held in set position for engagement in the slotted portion of a screw, it projects endwise beyond the driver blade. The screw is thus first engaged by the gripper blade and this engagement results in releasing the detent and permitting the gripper blade to rotate in gripping engagement.

It will be seen from the above brief description of the invention that the device is self-engaging with a screw and also self-resetting in response to starting movement of the screw.

These as well as other features and advantages of the invention will become more apparent from the following description of the presently preferred embodiment illustrated in the accompanying drawing which comprises the following views:

FIGURE 1, a side elevation of the screw engaging end of the device, the handle portion being broken off, and showing the device in normal or set position;

FIGURE 2, a side elevation similar to FIG. 1 but showing the device in engaging relation with the head of a screw;

FIGURE 3, a sectional elevation taken as indicated by the lines 3-3 of FIG. 1;

FIGURE 4, a plan view of the gripping end of the device taken as indicated by the arrow 4 of FIG. 3;

FIGURE 5, a section taken as indicated by the line 5-5 of FIG. 3;

FIGURE 6, a section taken as indicated by the lines 66 of FIG. 2, but showing the device in set rather than in engaging position;

FIGURE 7, a view similar to FIG. 6 but showing the device in engaging position with the screw; and

FIGURE 8, an end elevation showing the assembled relation between the driver blade stern and the spring.

The device illustrated includes a suitable handle which is not shown in full since the portion not shown corresponds to the handle portion of a screwdriver and may be designed as desired. A socket 12 is formed at the end of this handle, and an end fitting generally designated 14, has a portion 16 which is inserted within the socket 12 in such a way that the fitting in effect becomes an integral part of the handle. One way to accomplish this is to provide longitudinal serrations around the periphery of the portion 16 and to dimension this portion so that it is inserted within the socket with a press fit.

End fitting 14' also has a cylindrical outer portion 18 which acts as a pilot or bearing for a collar 20, extending within a bore 21 thereof to an extent limited by abutment means in the form of the inner end surface 41 of the collar 20 and a shoulder 42 on the end fitting 14.

End fitting 14 is also provided with an internal bore 22 which receives the stem 24 of a driver blade 25. Again a press fit is employed between the stem 24 and bore 22. so that the driver blade .25 in effect becomes an integral part of the handle 10, being rotatable therewith.

The outer end 26 of the driver blade 25 is enlarged, forming portions 27 which overlie the end of the collar 20, and the outer edge 28 of the driver blade is suitably shaped for engagement in the slotted portion of a screw. The device illustrated is designed to engage the slotted portion of a cross-slotted screw 30 of the type having slots 31 and 32 with inwardly tapered end walls and as is shown in FIGS. 3, 6 and 7, the outer edge 28 of the driver'blade is tapered for engagement in one of the slots 32 of the screw.

A pair of gripper blades 33 and 34, having similarly tapered edges 35, project from the outer end of the collar 20 and straddle the outer end 26 of the driver blade.

When the device is assembled, after the end fitting 14 has been secured to the handle, a spring guide 36. and spring 38 are inserted into the bore 21 of the collar 20, spring 38 having its inner end 39 (FIG. 8) formed so as to non-rotatably engage the stem 24 of the driver blade 25, and having its outer end37 formed so as to non-rotatably engage the collar 20. The collar 20, spring guide and spring are then slipped over the stem 24 of the driver blade, which engages the spring portion 39 as just described, the collar 20 is wound on the stem so as to place the spring 38 in torsion, and then the driverblade stem is inserted within the bore 22 of the end fitting as shown in FIG. 3, placing the spring 38 under compression.

Alternately, the collar 20, spring guide 36, spring 38 and driver blade 25 can be first assembled to the end fitting 14 to form a blade assembly which can then be pressed onto the end of the handle, the necessary force being transmitted from the collar 20 to the end fitting through the abutment surfaces 4142.

Thus the compression of spring 38 acts to urge the collar 20 outwardly of the handle and into engagement with the enlarged portions 27 of the driver blade 25. These portions 27 thus act to retain the collar and gripper blades in assembled relation with the handle. They also form part of a detent means, the end of the collar 20 being provided with a slot 44, which when engaged with the driver blade portions 27 holds the collar and gripper blade against rotation in a normal or set position in which the driver and gripper blades are at right angles to each other ready for engagement in the cross-slots 31 and 32 of the screw 30 as shown in FIG. 6. l

The slot portion 44 of the detent means also permits the collar to move axially on the bearing 22, leaving a clearance at 40 between the inner end 41 of the collar and the shoulder 42 of the end fitting, and placing the gripper blades 33 and 34 in a position where they project beyond the outer edge 28 of the driver blade as shown in FIGS. 1 and 3. When the device is inserted into engagement with the slots of the screw, the gripper blades 33 and 34 first bottom in the screw slot 46, resulting in axial movement of the collar 20 and disengaging the notch 44 from the driver blade portions 27.

The torsional force stored into the spring 38 then produces rotation of the collar 20 and gripper blades 33 and 34 relative to the driver blade 25. This rotation of the gripper blades is preferably in the direction of normal tightening rotation of the screw or clockwise as will be seen from a comparison of FIGS. 6 and 7, and brings both the driver and gripper blades into wedging engagement with opposite sides of one of the screw slots. Both driver and gripper blades are made relatively narrow in comparison to the width of the screw slot they engage. They are formed and hardened with relatively sharp gripping edges 48 and as a result the screw is firmly engaged and held in endwise relation to the handle of the device and can readily be inserted and started in the hole in which it is to be positioned.

As the screw is turned into the hole, the amount of turning moment that must be applied to the handle gradually increases and this increasing resistance to movement of the screw is imparted to the gripper blades 33 and 34 which initially are in driving position or relation with the screw as can be seen from FIG. 7. The result of this increasing resistance is to rotate the gripper blades back to their starting position and drive to the screw is transferred from the gripper blade to the driver blade. When the gripper blades move back to 90 degree relation with the driver blade, the slot 44 in the collar 20 falls into line with the portions 27 of the driver blade and the device automatically returns to reset position-in effect in response to the screw reaching a started position. The transfer of drives from the gripper to the driving blades can be sensed by one manipulating the device, and at the time of transfer the device is withdrawn from the slotted portion of the screw, thus allowing the collar 20 to move axially and place the detent means in engagement.

It is thus seen that the invention provides a screw starting device which is of simple construction, which snaps out of a set position into engagement with a screw in response to initial contact with the slotted portion thereof, which firmly holds the screw by the threaded portion in an endwise position for insertion into a hole, and which is self-returning to set position in response to driving or starting the screw in the hole.

While preferred embodiments have been described above in detail, it will be understood that numerous modifications might be resorted to without departing from the scope of the invention as defined in the following claims.

I claim:

1. A device for inserting and starting a cross-slotted screw in a hole comprising a handle, a driver blade fixed thereto, a collar mounted on said handle adjacent said driver blade for rotary and axial movement relative thereto, said driver blade including a transversely extending portion overlapping the outer end face of said collar and limiting axial movement thereof outward of said handle, a gripper blade carried by said collar, said gripper blade having portions located at each side of said driver blade, spring means between said collar and handle for normally urging said collar axially outward into abutment with said overlapping driver blade portion and for normally urging said collar and gripper blade rotatively in the direction of driving rotation of said screw, and detent means for holding said collar in a set position in which said gripper blade portions are substantially at right angles to and on either side of said driver blade, said detent means including the said end face of said collar and said overlapping driver blade portion and being engageable upon normally urged axial outward movement of said collar to a position in which said gripper blade projects endwise beyond said driver blade for initial engagement of said gripper blade with said screw, said detent means being releasable in response to such engagement.

2. A device for inserting and starting a cross-slotted screw in a hole, said device being of the type including a handle, a driver blade fixed thereto for rotation therewith, and a gripper blade carried for normally urged rotary and axial movement relative to the driver blade; characterized by said driver blade having a stem portion and an enlarged outer end provided with edges shaped for engagement with one slot of a cross-slotted screw, a collar having a central aperture through which the said driver blade stem extends in clearance relation, means mounting said collar on said handle for rotary and axial movement relative thereto, spring means for normally urging said collar rotatively on said handle and for normally urging said collar axially outward into abutment with the said enlarged outer end portion of said driver blade whereby said driver blade acts to retain said collar in assembled relation with said handle, detent means comprising a notch formed in the outer end of said collar for engagement with the said enlarged end portion of said driver blade, said gripper blade comprising a pair of blade elements carried by said collar in substantially right angular relation to said detent notch therein, said gripper blade elements straddling said enlarged end portion of said driver blade for engagement with the second slot of a cross-slotted screw, said gripper blade elements projecting outwardly beyond the outer edge of said driver blade when said detent notch is engaged therewith for initial engagement of said gripper blade elements with one slot of said screw, said collar being movable axially inward in response to such engagement to release said detent notch from engagement with the said enlarged end portion of said driver blade and permit said collar and gripper blade elements to rotate toward said driver blade thereby forcing said driver blade and gripper blade elements into engagement with the sides of the slots of said screw.

3. A device for inserting and starting a cross-slotted screw in a hole comprising a handle, and a blade assembly, said blade assembly including an end fitting adapted to be fixedly secured to said handle, a collar carried by said end fitting for rotary and axial movement relative thereto, a pair of gripper blade elements projecting from the outer end of said collar with a central slot therebetween, said gripper blade elements each having outer edge portions shaped for engagement with one slot of a cross-slotted screw, a coil spring mounted within said collar and having one end secured in fixed relation therewith, a driver blade having a stem portion and an enlarged end portron, said enlarged end portion including edges shaped for engagement with the other slot of a cross-slotted screw, a central aperture formed in said collar and for receiving the said stem portion of said driver blade, said driver blade stem portion extending through said spring in fixed relation with the other end thereof and being secured to said handle end fitting with the enlarged end portion of said driver blade positioned between said gripper blade elements and in overlapping relation with the outer end of said collar whereby said driver blade acts to retain said collar in assembled relation with said end fitting with said spring in compression and torsion, and detent means for holding said collar in a set position in which said gripper blade elements extend at substantially right angles to said driver blade, said detent means including the said enlarged 5 driver blade end portion and a notch in said collar and being engageable upon normally urged axial outward movement of said collar by said spring to a position 'wherein said gripper blade elements project endwise beyond said driver blade end portion for initial engagement of said gripper blade with one slot of said screw, said detent means being releasable in response to such engagement by axial inward movement of said collar to permit said collar and gripper blade elements to rotate toward said driver blade thereby forcing said driver blade and gripper blade elements into engagement with the sides of the slots of said screw.

4. A screw starting device according to claim 3 fur ther characterized by said end fitting having a portion adapted to be placed into engagement with said handle and abutment means between said end fitting and collar for limiting axial inward movement of said collar on said end fitting.

References Cited in the file of this patent UNITED STATES PATENTS 

